In the Creed we say: For us men and for our salvation
he came down from heaven,
and by the Holy Spirit was incarnate
of the Virgin Mary,
and became man
We know that St Joseph was only the foster father of Jesus. This tells us that Jesus only had one earthly biological parent. In modern medicine we learn that it is very difficult for a mother to give birth without a biological father. There are certain theories about how it could happen but they seem to be very rare (if they ever happened). I have never even heard about a theologian who actually talked about this issue. All I know is that Jesus did not have a normal birth.
What does the Catholic Church say about this?
Tack, for your question.
Since you are familiar with Catholic teaching, I need not emphasize the antiquity of the dogma of the Blessed Virgin as a virgin before, during, and after the birth of Jesus.
You asked a question about which I had never considered. I am not aware of Catholic teaching on the physiology of requirements for a virgin conception.
The Dogpile website provided a wide range of information on "Virgin Birth."
Non-believers are of two kinds:  a myth borrowed from pagan mythology;  a misunderstanding of Isaiah.
Believers are of two kinds:  a complete understanding of the biblical passage;  examiners of the physical possibility of a human virgin conception.
Among this last group are several explanations of what gynecological events would have to occur and the remotest possibility of such an occurrence. A recent summary in Popular Science provided a current status of the medical situation.
Nice to hear from Stockholm, which I visited many years ago. My grandparents Alfred Lind and Else Andersdotter came to USA from Blekinge in the 1890s.
Best wishes, Andrew.